This invention relates to a novel interpolymeric poly(n-alkylacrylate) pour depressor, to wax containing residual fuel oil compositions of reduced pour point containing said pour depressor and to making greater utilization of low sulfur, high wax content residual fuel oils.
As is well known, air pollution has many contributing causes. One of these is the relatively high amount of sulfur dioxide contained in stack gases resulting from heavy residual fuel oil combustion at industrial plants such as utility power plants. Recognition of this cause has led to regulations concerning the sulfur content of heavy residual fuel oils in the United States and in some European countries. To comply with these regulations, fuel oil producers are employing low sulfur, high pour, waxy crudes, particularly those produced in the North African oil fields. The main problem confronting the use of these waxy crudes is their high pour point, that is, of the order of 80.degree. to 100.degree.F. and higher.
In order to render these residual fuel oils feasible for transport and use, pour points of the order of about 50.degree.F. and less, preferably less than 30.degree.F., are required. This reduction in pour point is often accomplished through the use of pour depressors. However, many of the pour depressors which are effective in non-waxy fuels, for example, copolymers of dodecyl and octadecyl methacrylates and interpolymeric polymers of alkyl acrylates wherein a substantial portion of the alkyl groups, i.e., greater than about 35%, containing more than 24 and less than 20 carbons and/or are branched chain are relatively ineffective. Thus, there is a continuing need in this area for the finding of low cost pour depressors that are significantly effective in lowering the pour point of high pour waxy residual fuels.